Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.1 (RNase)
 16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A comparison was made between rats fed diets containing either 5% casein or 25% casein, both being supplemented with DL-methionine, from the first day of pregnancy. Livers of dams killed on days 7, 14, and 21 and whole fetuses on days 12, 14, and 21 were weighed, analyzed for protein, RNA and DNA content and assayed for ornithine decarboxylase (ODC) and S-adenosyl-L-methionine decarboxylase (SAMD). Free and total alkaline ribonuclease activity were also measured in the maternal livers. Malnutrition reduced the characteristic increase in content of DNA, RNA and protein in the maternal liver and fetus. In control rats total hepatic RNase activity increased and free RNase activity decreased during late pregnancy. In the deprived group, total activity decreased and free activity increased during late pregnancy. Liver and fetal ODC and SAMD activities were reduced by undernutrition. These studies show that malnutrition reduced both growth and the accretion of RNA in livers and fetuses of rat dams. These changes coincide with a reduced activity of polyamine synthesizing enzymes suggesting that there is a functional relationship between polyamines and RNA. High hepatic free RNase activity in malnourished dams may help to limit any build up in RNA content.
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PMID:Effects of malnutrition on some aspects of RNA metabolism in the maternal liver and fetal tissues at different stages of pregnancy in the rat. 89 66

A new rapid method for the quantitative and routine determination of free amino groups in intact pure proteins has been developed. Primary amino groups are labeled with fluorescamine and the labeled groups are detected by absorption spectroscopy in the range 375-390 nm. The amino group concentration can be determined in a few minutes without hydrolyzing the labeled protein and extracting a lysine derivative. The method was tested with the following proteins: lysozyme, alpha-lactalbumin, beta-lactoglobulin, bovine serum albumin, ribonuclease, ribonuclease-S-peptide, and alphasl-casein B. Application of this method to the estimation of available lysine is discussed.
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PMID:New method for determination of free amino groups in intact pure proteins: relationship to available lysine. 99 78

Strains from type culture collections and clinical isolates belonging to the Aeromonas and Pseudomonas genera were identified with conventional tests. Production of extra-cellular enzymes and haemolysins were detected by simple plate agar methods. The following enzymes were found to be of special value for a rapid and simple classification of certain species in both genera: potease (casein and gelatin agar), lecithinase (lecithin agar), and deoxyribonuclease (DNA agar). Elastase, staphylolytic enzyme, lipase, ribonuclease, amylase, and egg yolk reaction were other enzymes studied. However, these tests were not positive for more than 90% of any species. A. hydrophila, A. salmonicida, and P. aeruginosa were haemolytic on agar containing rabbit erythrocytes.
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PMID:Characterization of three Aeromonas and nine pseudomonas species by extracellular enzymes and haemolysins. 117 Apr 82

The effect of a high protein diet (20% casein + D,L-methionine) administered to Wistar rats during pregnancy on some aspects of cellular growth and RNA metabolism of progeny has been studied. Comparisons were made with well-nourished (10% casein + D,L-methionine) controls. Newborns individual weight, litter weight and number of newborns per litter were unmodified. However, neonate protein content dropped significantly when compared with controls. Both rate of DNA and number of nuclei were unchanged. Protein/DNA ratio (cellular size relative to protein) decreased, which might have led to an atrophy phenomenon, even if the newborn weight/number of nuclei ratio was not modified. Acid DNase activity rose, bringing about DNA breakdown. Total RNA content together with RNase activity fell in newborn from rats suffering high protein diet. Moreover, protein synthesis capacity (RNA/protein ratio) did not change. These results suggest that the administration of a high protein diet to pregnant rats lead to changes in newborn protein rate and nucleic acid turnover by modulating specific nuclease activity.
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PMID:[High protein diet in pregnancy. Effects on neonatal metabolism]. 242 60

The effect of a high protein diet (20% casein + D,L-methionine) administered to adult Wistar rats on some aspects of muscle RNA metabolism has been studied. Body weight increased in spite of lower intake. However, gastrocnemius muscle remained unmodified, although protein content increased. Total RNA decreased in the whole muscle although RNA/DNA ratio did not change. Protein synthesis capacity diminished 81% relative to controls in spite the fact that an excessive amount of available amino acids exists. RNA loss might depend on a high catabolism, since acid RNase activity increased over control values. Therefore, it may be concluded that a high protein diet leads to a lower protein synthesis capacity through an elevated RNA breakdown.
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PMID:[Changes in the metabolism of muscle RNA in rats given a high protein diet]. 244 42

Casein kinase II purified from nuclei of Xenopus laevis oocytes is inhibited by several specific nucleic acids. This kinase, the main phosphorylating activity of the oocyte nucleus, is markedly inhibited by poly U at 10 micrograms/ml, and this polymer is a competitive inhibitor of the phosphorylation of the substrate casein (Kiapp 80 nM). M 13 phage ssDNA and unfractionated yeast tRNA also inhibit between 50 and 200 micrograms/ml. Poly C, poly A, poly AG, dsDNA and Escherichia coli rRNA do not alter activity significantly at similar concentrations. Inhibitions are reversed by RNase (poly U, tRNA) or S1 nuclease (ssDNA). Oocyte casein kinase I or rabbit cAMP-dependent protein kinase are not inhibited by poly U at 200 micrograms/ml. The sensitivity of the casein kinase II to these inhibitors suggests a regulatory role for nucleic acids in nuclear phosphorylation reactions.
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PMID:Nucleic acids can regulate the activity of casein kinase II. 279 84

Methods have been developed to isolate high-molecular-weight pre-mRNAs from lactating mammary gland, a tissue high in RNase levels. These methods involved isolation of nuclei at -20 degrees C in 50% glycerol, and nucleic acid extraction using a guanidine thiocyanate-CsCl protocol. Specific RNAs were detected using alpha-, beta-, and gamma-casein and whey acidic protein nick-translated cDNA and genomic DNA probes by hybridization in situ to pre-mRNAs fractionated on agarose gels containing 10 mM methylmercuric hydroxide. Using these techniques it was possible to isolate poly(A)-containing gene-sized primary transcripts in the case of the two smaller genes, beta-casein and whey acidic protein. A very complex pattern of pre-mRNAs was observed for the beta-casein transcripts, including detection of a species which may represent an excised intron. Probes for the alpha- and gamma-casein genes revealed much lower abundance and complexity of RNA precursors. These methods have proven useful in the initial analysis of RNA processing of these hormonally regulated milk protein gene transcripts.
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PMID:Isolation and characterization of milk protein nuclear RNAs in rat mammary gland. 287 72

Degradation of intracellular proteins via the ubiquitin- and ATP-dependent proteolytic pathway involves several steps. In the initial event, ubiquitin, an abundant 76-residue polypeptide is covalently linked to the protein substrate in an ATP-requiring reaction. Proteins marked by ubiquitin are selectively proteolyzed in a reaction that also requires ATP. Ubiquitin conjugation to proteins appears also to be involved in regulation of cell cycle and cell division, and probably in the regulation of gene expression at the level of chromatin structure. We have previously shown (Ciechanover, A., Wolin, S. L., Steitz, J. A., and Lodish, H. F. (1985) Proc. Natl. Acad. Sci. U. S. A. 82, 1341-1345) that transfer RNA is an essential component of the ubiquitin pathway. Ribonucleases strongly and specifically inhibited the degradation of 125I-labeled bovine serum albumin, while tRNA purified from reticulocyte extract could restore the proteolytic activity. Specifically, pure tRNAHis isolated by immunoprecipitation with human autoimmune serum could restore the proteolytic activity. Here we demonstrate that tRNA is required for conjugation of ubiquitin to some but not all proteolytic substrates of the ubiquitin mediated pathway. Conjugation of 125I-labeled ubiquitin to reduced carboxymethylated bovine serum albumin, alpha-lactalbumin, and soybean trypsin inhibitor was strongly and specifically inhibited by ribonucleases. Consequently, the ATP-dependent degradation of these substrates in the cell-free ubiquitin-dependent reticulocyte system was inhibited as well. Addition of tRNA to the ribonuclease inhibited system (following inhibition of the ribonuclease) restored both the conjugation activity and the ubiquitin- and ATP-dependent degradation of these substrates. Conjugation of ubiquitin to some endogenous reticulocyte proteins was also inhibited by ribonucleases and could be restored by the addition of tRNA. In striking contrast, the conjugation of radiolabeled ubiquitin to lysozyme, oxidized RNase A, alpha-casein, and beta-lactoglobulin was not affected by the ribonuclease treatment, and the degradation of these substrates was significantly accelerated by the ribonucleases. These findings indicate that there are at least two distinct ubiquitin conjugation systems. One requires tRNA, and the other is tRNA independent. These pathways, however, must share some common component(s) of the system, since the inhibition of one system accelerates the other. The possible function of tRNA in the selective conjugation reaction and the possible role of the two distinct ubiquitin marking mechanisms are discussed.
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PMID:Transfer RNA is required for conjugation of ubiquitin to selective substrates of the ubiquitin- and ATP-dependent proteolytic system. 300 81

Galactosyltransferase (EC 2.4.1.22) requires bivalent metal ions for its activity. However, preparations of this enzyme solubilized from Golgi membranes of lactating rat mammary gland were shown to be activated not only by Mn2+, Ca2+ and Mg2+, but also by spermine, spermidine, lysyl-lysine, ethylenediamine and other diaminoalkanes, and by a range of basic proteins and peptides, including clupeine, histone, polylysine, ribonuclease, pancreatic trypsin inhibitor, cytochrome c, melittin, avidin and myelin basic protein. Both N-acetyl-lactosamine synthetase and lactose synthetase activities were enhanced. A basic protein fraction was isolated from bovine milk and shown to activate galactosyltransferase at low concentrations. The polyanions ATP, casein, chondroitin sulphate and heparin reversed the activation of galactosyltransferase by several of the above substances. Galactosyltransferase, assayed as a lactose synthetase, showed a 10-fold greater affinity for glucose when Mn2+ ions were replaced by clupeine or by ribonuclease as cationic activator. Evidence was obtained for the presence of an endogenous cationic activator in solubilized Golgi membrane preparations which evoked a similar low apparent Km,glucose. The findings are discussed in the light of cationic activations of glycosyltransferases generally, of the porous nature of the Golgi membrane, and of the unlikelihood of bivalent metal ions being the physiological activators of galactosyltransferase. It is suggested that the natural cationic activator of lactose synthetase may be a secretory protein acting in a manner analogous to the enzyme's activation by alpha-lactalbumin. A scheme is proposed for the two-stage synthesis of lactose and phosphorylation of casein within the cell, to accommodate the apparent incompatibility of these two processes.
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PMID:Cationic activation of galactosyltransferase from rat mammary Golgi membranes by polyamines and by basic peptides and proteins. 310 66

1. Trypsin and ribonuclease were filtered through dextran gel (Sephadex G-100) columns in the absence and presence of their respective substrates. In the presence of their high-molecular-weight substrates the enzymes emerged earlier from the columns. This appeared to be due to the reversible formation of specific enzyme-substrate complexes. 2. The possibility of separation of an enzyme from other proteins with similar molecular weights was demonstrated with trypsin and cytochrome c in the presence of casein.
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PMID:Dextran-gel filtration of enzymes in the presence of their high-molecular-weight substrates. 593 53


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